1893. | NEW YORK ACADEMY OF SCIENCES. 101 
regards the remains of Diatomacez which they contain, although 
they differ somewhat in the assembly of genera and species, as 
is the case with all the lacustrine sedimentary deposits of the 
post-glacial area of the Middle and Eastern States. 
In my previous paper I described more particularly the de- 
posit existing near Hinckley, in the southern part of Herkimer 
county, in which the most prominent forms had been identified. 
The probability is that a complete list of the forms distributed 
over an area as large as the one we have now under consider- 
ation would include practically all of the species which have 
been found in the many deposits scattered over the surface of 
New York and the New England States. The main difference 
observable in comparing the earths from the northern part of 
Herkimer county with the one from Hinckley is, that the Hinck- 
ley deposit contains very few individuals of the genus Suwrirella, 
while the Northern deposits are generally quite rich in this 
genus. This is especially the case with the specimens from 
Hawk Lake and the lake north of Big Crooked. In these the 
Surirelle appear to make up the bulk of the material and are 
crowded in the field of view. They are less conspicuous, how- 
ever, in the specimens from Roilly Pond and Beaver Meadow, 
and still less so in the others. In all of the deposits the free 
forms of diatoms are predominent, which is, of course, to be ex- 
pected in specimens from a still water habitat. As I mentioned 
in my previous paper, these are mostly of the genera Navicula, 
Stauroneis, Cymbella and Hunotia, to which I may now add 
Surirella. I then spoke of these as solitary and motile, when 
it would have been sufficient to designate them merely as free, 
by which is meant entirely unattached to rocks, weeds, etc. 
Along with these free forms we find a scattering of those which 
are classed as filamentous, stipitate and adnate, such as Jelosira, 
Gomphonema and Epithemia, all of which are, during their 
adult period at least, anchored or attached, and which, there- 
fore, belong in moving water. This association of free and fixed 
forms is an indication that while the deposits were in the main 
laid down in still water, they were, nevertheless, contributed to 
by streams which fed the lakes or wandered through them. 
I submit herewith samples of all the earths referred to in this 
paper in the condition in which they have come to me, and also 
slides for examination under the microscope, showing each 
earth in its natural state and also after the usual treatment to 
separate the diatoms from the amorphous matter. 
